paper

Water maser emission in IC342

arXiv:astro-ph/0201449 · doi:10.1051/0004-6361:20020199

Abstract

The detection of 22 GHz water vapor emission from IC342 is reported, raising the detection rate among northern galaxies with 100 micron IRAS point source fluxes > 50 Jy to 16%. The maser, associated with a star forming region 10-15 arcsec west of the nucleus, consists of a single 0.5 km/s wide feature and reaches an isotropic luminosity of 0.01 solar luminosity (D = 1.8 Mpc). If the time variability is intrinsic, the maser size is < 1.5 x 10^(16) cm (< 0.5 mas) which corresponds to a brightness temperature of > 10^(9) K. The linewidth, luminosity, and rapid variability are reminiscent of the 8 km/s super maser in Orion-KL. A velocity shift of 1 km/s within two weeks and subsequent rapid fading is explained in terms of a chance alignment of two dense molecular clouds. Observations at 22 GHz toward Maffei2 are also reported, yielding a 5 sigma upper limit of 25 mJy for a channel spacing of 1.05 km/s.

7 pages including 4 figures, accepted for publication in A&A Main Journal

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